The invention relates to an apparatus for the combustion of vanadium-containing fuels and a method for the combustion of vanadium-containing fuels.
Vanadium-containing fuels are obtained as residues during pretroleum refining. These residues are generally burned in spiral flow or rotary heaters and vanadium and compounds thereof, together with other recyclable constituents of the residues are obtained in slag and ash form, which can advantageously undergo further treatment. Simultaneously the heat released during combustion can be recovered.
A spiral flow heater for the heat treatment of carbon-containing residues from petroleum refining is known from DE 41 14 171 C2. Carbon-containing materials with non-flammable constituents and pollutants are supplied in a predetermined particle size tangentially in a delivery air flow to a combustion chamber and burned at temperatures above the slag melting point. The combustion air is tangentially blown in such a way that a direct contact and sticking of slag to an inner lining of the combustion chamber are avoided. As a result of cooling, the slag is discharged in solid form.
It has been found that during the combustion of vanadium-containing carbon black dust in a spiral flow furnace spontaneously liquid slag is produced at the common burner chamber temperatures.
The spontaneous slag sticking is particularly disadvantageous in the vicinity of the supply nozzles for the pulverized fuel-air mixture and the air nozzles for the combustion air. Even after relatively short operating periods the nozzles suffer slag penetration leading to a restriction and disturbance to heater operation.